Power transmission system embodying hydraulic couplings



H. SINCLAIR March 7, 1939.

POWER TRANSMISSION SYSTEM EMBODYING HYDRAULIC COUPLINGS Filed March 18, 1937 2 Sheets-Sheet l H. SINCLAIR March 7, 1939.

2,149,369 POWER TRANSMISSION SYSTEM EMBODYING HYDRAULIC coUPLINGs Filed March 18, 1937 2 Sheets-Sheet 2 Patented Mar. 7, 1939 PATENT OFFICE A POWER TRANSMISSION INGHYD RAULIO SYSTEM EIVIBODY- COUPLIN GS Harold Sinclair, London, England Application March 18, 1937, Serial No.

In Great Britain March 24, 1936 16 Claims. (Cl. 60-54) The present invention relates to power transmission systems embodying a hydraulic coupling V of the kinetic (Fttinger) type.v

,It is often desired to vary the torque transn''is'sion capacity of such a system, and for this purpose it is known to provide a torque-reducing control member. In one known arrangement this has the form of a hydraulic control member, such for example as a slidable ring valve, which can be operated to vary the circulation of the working liquid within the hydraulic coupling or a filling or emptying valve which can be operated to vary the liquid content of the working circuit rangement the torque-reducing control member has the form of a brake operable for arresting or restraining the rotation of the driven part of the hydraulic coupling, such a brake being adapted to vary the torque transmission capacity of the system as a whole, since its eliect is to intercept a part of the torque between the'driving and the driven shafts.

The term torque-reducing control member is hereinafter employed to denote either a ring valve or equivalent device for throttling the circulation of liquid within the coupling, or means operable for varying the filling of the working circuit of the coupling, ora brake associated with the driving or the driven part of the coupling.

An object of the present invention in certain embodiments thereof is to provide an improved arrangement for operating such torque-reducing control members. v

Hydraulic couplings may be used in power transmission systems of the kind in which, under certain circumstances, the element that is normally the driven` machine temporarily returns powerto the driving machine which is thus liable to be run at an excessive speed and damaged. For example, a ships steering gear may comprise a steam turbine coupled to a hydraulic pump which drives a reversible hydraulic motor` operatively connected with the helm. With such an arrangeconditions, the direction of the torque acting between the turbine and the hydraulic pump is reversed and the turbine is driven at a dangerously highv speed. Another example of a system in which reversal of torque can take place, withA risk ofv injury to the driving machine, is a Ward-Leonard winding-engine driven'by a steam turbine or a Diesel engine f through a hydraulic coupling.

A further objectA of the present invention in certain other embodiments thereof isto proplied to the system.

'I'he present invention, in its broad aspect con'- 5 sists in providing a hydraulic coupling of the kinetic type with a torque-reducing control member (as herelnbefore defined) and with a dierential mechanism which is so arranged that it is not required to transmit any substantial forward 10 driving torquefrom the driving shaft to the driven shaft of the coupling and which, by employing part of the power applied to the hydraulic coupling, serves to operate, either at will or automatically, the torque-reducing con- 15 trol member.

By the term a mechanism is xed by constraining the remaining element or all the remaining elements to move at uniform speeds.

member) in a hydraulic coupling, the differential mechanism connects together rstly the ring valve, secondly one of the rotatable vaned 30 elements of the hydraulic coupling, and thirdly a brake drum which can be restrained at will.

Alternatively, where the invention is applied to the reduction of over-running torque in a power transmission system embodying a hydraulic coupling, the differential mechanism is adapted to connect together rstly the driving part of the hydraulic coupling, secondly the driven part of the hydraulic coupling, and thirdly the torque-reducing control member, the dilerential 40 mechanism being responsive to reversal of slip in the hydraulic coupling and serving, upon reversal of torque-load in the system, to actuate the torque-reducing control member so as to reduce the over-running torque transmitted to the driving machine.

The invention will be further described with reference to the examples shown in the accompanying diagrammatic drawings, in which:

Fig.` 1 is a sectional side elevation of part of the power transmission system of a vehicle,

Figs. 2 and 3 are respectively sectional side elevations of parts of two hydraulic couplings adapted to limit overrunning torque, and

Fig. 4 is a diagram of a power transmission system adapted to limit overrunning torque.

Fig. 1 shows an arrangement providing for servo operation of the ring valve of a hydraulic coupling. This arrangement also embodies a subsidiary feature, namely, means for imparting a slow backward rotation of the driven shaft of the coupling for a purpose to be hereinafter described.

In Fig. l the impeller I2 of the hydraulic coupling is fixed directly to the shaft II of an internal-combustion engine I0, while the runner I3 is fixed to a driven shaft I4. The impeller and runner each consist ofan annular dished shell provided with radiating varies, and these shells are juxtaposed to form a working circuit in the form of a toroidal ring. The driven shaft I4 is splined to the input shaft I5 of a mechanical change-speed gearing I6 having jaw clutches, such as I1, for selecting the various speeds. On the back of the runner shell is xed a dished drum I8 which normally accommodates a ring valve I9 slidable into the circuit through an annular slot 20 in the runner shell. A dished casing 2I is secured to the periphery of the impeller and houses this drum.

This arrangement comprises a differential mechanism connecting together four elements, namely, the driving part and the driven part of the hydraulic coupling, the slidable ring valve, and a brake drum 34. Between the drum I8 and the runner I3 are fixed a plurality of cylindrical pins, such as 22, distributed around and parallel to the coupling axis. A nut 23 which has a lefthand thread is fixed to a disk 24 slidably mounted on the pins 22 so as to rotate with the runner and forming part of the ring valve I9. A sleeve 25 surrounds the driven shaft I4 and is threaded externally at 26 where it engages with the nut 23. Thrust washers 21 and 28 prevent the sleeve 25 from moving axially and it is rotatable relatively to the runner. On the sleeve 25 is fixed a small sun wheel 29 in constant mesh with the larger of a pair of planet wheels 30 and 14| integral with one another and journalled on a pin 32 fixed to the shell 2l. The smaller planet wheel 3I meshes with a larger sun wheel 33 which is iixed to the brake drum 34 adapted to be held stationary by a brake shoe 35 (actuated by control means not shown) A spiral spring 36 connects a drum 31, keyed to the sleeve 25, with a hub 38, pinned to the )shaft I4.

When the engine shaft II is rotating clockwise (as viewed from the impeller end` of the device) and the drum 34 is braked, the planet wheel 3| rolls round the fixed sun wheel 33 and the planet wheel 30 imparts a slow backward rotation to the sun wheel 29 and the sleeve 25. This sleeve therefore screws the nut 23 towards the impeller I2, causing the ring valve I9 to be inserted into the circuiti; at the same time the relative rotation of the sleeve 25 and the runner tensions the spring 35. If the runner ils stationary, the movement of the ring valve is relatively slow; if the runner is rotating forwards, the movement of the ring valve is faster. When the ring valve is fully closed, the brake drum 34 may slip under the shoe 35. Where, however, it is required to disengage a gear of the changespeed gearing I6 when the engine shaft II is running and the vehicle is stationary, the drag torque existing on the gearing may be relieved by maintaining the brake firmly applied after the ring valve is fully closed. As a result the nut 23,..having reached the limit of its travel towards the left, is caused to rotate slowly in the reverse direction and thus to impart a. similar rotation to the runner, with the result that the mechanical change-speed gearing is relieved of torque load. When the brake shoe 35 is disengaged, the spring 36 acts to return the ring valve to its inoperative position.

Where it is unnecessary to relieve drag torque on'gearing associated with the hydraulic coupling, the brake can be arranged to act on the drum 31, the planetary gearing 29, 30, 3|, 33 and the brake drum 34 being superuous. Re-

. straint by the brake of the drum 31 while the driven shaft is rotating closes the ring valve, the operative elements of the differential mechanism under these circumstances being the differential screw-and-nut mechanism.

Where a relatively rapid reversal of torque is,

apt to occur, as in the kind of ships steering gear hereinbefore referred to, the invention may be carried into effect by providing, between the steam turbine and the hydraulic pump, a hydraulic coupling having a ring valve of known type, or like element which is movable into the working circuit of the coupling to throttle the circulation of liquid therein and thus to reduce the torque transmission capacity of the coupling, this ring valve being in the inoperative position when power is being transmitted from the turbine, and adapted to move into its' operative position when the direction of torque is reversed and the speed of the driven coupling part consequently exceeds that of the driving coupling part.

The means for actuating the ring valve, or other device for preventing excessive overrunning torque from reaching the driving machine, may comprise two co-operating screw-threaded elements mounted co-axially with the coupling parts, one of these screw-threaded elements being slidable longitudinally of the coupling, and operatively connected with the torque-limiting means, while the other screw-threaded element is restrained from moving longitudinally relatively to the coupling, a slipable driving connection being provided between one or the other of the screw-threaded elements and the driving (or the driven) part of the coupling, while the remaining screw-threaded element is coupled for rotation with the driven (or the driving) part of the coupling, whereby these screw-threaded elements are constrained to rotate relatively to one another upon reversal of slip in the coupling.

Thus in the arrangement shown in Fig. 2, a driving machine Illa, having a shaft IIa, is coupled to -a driven machine 40, having a shaft I4a, by a hydraulic coupling having a vaned impeller I2a xed to the shaft IIa and a vaned runner I3a fixed to the driven shaft I4a which is provided with\ a right-handed screw-threaded portion 4I. Co-operating with the screw 4I is a nut 42 operatively connected by a spider 48 with a ring valve I9a which is normally housed in the space between the runner and a dished casing 2 Ia fixed to the impeller. The nut is provided with splines 43 with which engages an internally splined boss 44. To this boss is fixed a friction ring 46 which is lightly pressed by a pressure plate 45, loaded by springs, such as 41, against the casing 2Ia.

When the shaft I Ia is rotating in the clockwise direction, as viewed from the left of Fig. 2, and the slip is in the normal direction, the ring valve I9a is held in its inoperative position, as shown,

istops slipping and moves the the friction clutch 45, 46 slipping and the nut 42 rotating with the driven part. When the driven machine begins to return power to the driving machine, the slip reverses, and momentarily stops slipping and rotates the nut 42 relatively to the driven shaft so that the ring valve is moved into its operative position, obstructs the flow of the working liquid, and vthus reduces the overrunning torque transmitted. If the driven machine continues to overrun, the friction clutch begins to slip as soon as the ring valve has entirely closed the circuit. When the slip is restored to its normal direction, the clutch again momentarily ring valve into its inoperative position.

The coupling shown in Fig. 3 is of the kind in whichr-the liquid content can be varied during operation In this example the impeller I2b,

:which is fixed to the driving shaft I Ib, ."-bya casing 2lb xed is enclosed to the runner |3b. Liquid can be'gadmitted to the coupling from a pressure 'siipplyrthr'ough a valve 50, a manifold 5| embrac- `igthe'diivenshaft |4b, and ducts 52 in this shaft.

Thecoupling is of vthe known core-tube emptying typ'e having the core guide member 53 that rotates with the runner shaped to form an annular channel 54 opening towards the coupling axis, this During normal clutch operation. The impeller I 2c, which is xed to the dr1ving shaft Hc, is enclosed by a casing 2Ic xed to the runner I 3c. Liquid can be admitted to the the friction clutch When the slip in the hydraulic coupling is in the normal direction, the parts are in the congurat1on shown, the valve 66 being op 66. In consequence, liquid is unable to flow into the coupling, so that the liquid content diminishes.'

Fig. 4.- shows also 68, the arslip reverses I 01ans:

1. A power transmission applied to said coupling.

2. A power hydraulic coupling of the kinetic parts, said torque-reducing control member, and said brakeable member, and

servo operation of said control means.

4. A power transmission system comprising a hydraulic coupling of the kinetic type having a rotatable vaned driving part and a rotatable vaned driven part, said parts co-operating to form a working circuit, control means movable within said circuit for throttling the circulation therein, a rotatable brakeable member, differential mechanism connecting together said vaned driving part, said vaned driven part, said control means and said brakeable member, means operable to restrain rotation of said brakeable member, and an elastic coupling device connecting together two of said differentially connected parts, the ratios of said diierential mechanism being such that, when said vaned driving part is rotating laster than said vaned driven part and said brakeable member is arrested, said control means are operated to throttle said circuit, and said elastic coupling device serving to return said control means when said brakeable member is released.

5. A power transmission system comprising a hydraulic coupling of the kinetic type having a rotatable vaned driving part and a rotatable vaned driven part, said parts co-operating to form a working circuit, a ring valve movable into said circuit, a screw-threaded member which is movable axially of said coupling, which is operatively connected with said ring valve, and which is constrained to rotate with said vaned driven part, a second screw-threaded member, which is engaged with said first-mentioned screw-threaded member, a brakeable member, a planetaryfgear having three co-operating elements rotatable relatively to one-another and connected respectively to said second-mentioned screw-threaded member, to said vaned driving part, and to said brakeable member, means operable to restrain rotation of said brakeable member to cause said ring valve to move into said circuit when said driving part is rotating faster than said driven part, and means for moving said ring valve out of said circuit.

6. A power transmission system comprising a hydraulic power transmitter of the kinetic type having a rotatable vaned driving part, a rotatable vared driven part, a sun wheel connected for rotation with said driven part, afsecond sun wheel, of only slightly larger diameter than said rstmentioned sun wheel, two co-axial planet wheels constrained to rotate together and meshing respectively with said sun wheels, a carrier on which said planet wheels are journalled and which is connected to said driving part, and control means operable for restraining the rotation of said second sun wheel to cause said driven part to rotate slowly oppositely to said driving part.

7. A hydraulic coupling ofthe kinetic type comprising a rotatable vaned driving part, a rotatable vaned driven part, said parts co-operating to form a working circuit for coupling liquid, a ring valve operable for throttling said circuit, a brake drum, means operable for restraining rotation of said v drum, and differential mechanism which connects said driving part, said driven part, said ring valve and said brake drum and which, when said brake rum. is restrained, employs energy derived from said driving part to close said ring valve and thereafter to rotate said driven part oppositely to its normal direction of rotation.

8. A power transmission system comprising a driving machine, a driven machine, a hydraulic coupling of the kinetic type connecting said machines together, a torque-reducing control mem-l ber, differential mechanism connecting together said driving machine, said driven machine and seid control member, said differential mechanism serving automatically, on reversal of slip in said coupling, to actuate said control member so as to reduce the overrunning torque on at least said driving machine.

9. A hydraulic coupling of the kinetic type having a rotatable vaned driving part, a rotatable vaned driven part, said pari/s tzu-operating to form a circuit for working liquid, a control member operable for throttling the circulation of liquid in said circuit, and mechanical drSerential mecha.- nism responsive to reversal of slip in said coupling for actuating said control member.

10. A power transmission system comprising a driving machine, a driven machine, a hydraulic coupling of the kinetic type having a vaned driving part coupled to said driving machine and a vaned driven part coupled to said driven machine, a torque-reducing control member, two co-operating screw-threaded elements mounted co-axlally with said coupling, one of said elements being slidable longitudinally of said coupling and operatively connected with said control member, while the other of said screw-threaded elements is restrained from moving longitudinally of said coupling, and a slipable driving connection between one of said screw-threaded elements and one of said vaned coupling parts, the other of Ysaid screw-threaded elements being coupled for rotation with the other of said vaned coupling parts,

whereby said screw-threaded elements are constrained to rotate relatively to each other and actuate said control member upony reversal of slip in said hydraulic coupling.

11. A hydraulic coupling of the kinetic type having a rotatable vaned driving part, a rotatable i vaned driven part, said parts co-operating to form, a circuit for working liquid, a control member operable for varying the liquid content in said circuit, and mechanical differential mechanism responsive to reversal of slip in said coupling for actuating said control member.

l2. A power transmission system comprising a driving machine, a driven machine, a hydraulic slip coupling connecting said machines together, a control member operable for braking one of said machines, and mechanical differential mechanism connecting together said driving and driven machines and said control member, and responsive to reversal of the direction of slip in said coupling for actuating said control'member.

13. A hydraulic coupling of the kinetic type having a vaned driving part, a vaned driven part, said parts co-operating to form a working circuit for coupling liquid, a control member operable for throttling the circulation of liquid in said circuit, two co-operating screw-threaded elements mounted co-axially with said coupling, one of said elements being slidable longitudinally of said coupling and operatively connected with said control member, while the other of said screw-threaded elements is restrained from moving longitudinally of said coupling, and a slipable driving connection between one of said screw-threaded elements and one of said vaned coupling parts, the other of said screw-threaded elements being coupled for rotation with the other of said vaned coupling parts,

whereby said screw-threaded elements are constrained to rotate relatively to each other and actuate said control member upon reversal of slip in said hydraulic coupling.

14. A hydraulic coupling of the kinetic type having a vaned driving part, a vaned driven part, said parts co-operating to form a working circuit for coupling liquid, a control member operable for varying the liquid content of said circuit, twocooperating screw-threaded elements mounted coaxially with said coupling, one of said elements being slidable longitudinally of said coupling and operatively connected with said control member, while the other of said screw-threaded elements is restrained from moving longitudinally of said coupling, and a slipable driving connection between one of said screw-threaded elements and one oitl said vaned coupling parts, the other of said screwthreaded elements being coupled for rotation with the other of said vaned coupling parts, whereby said screw-threaded elements are constrained to rotate relatively to each other and actuate said control member upon reversal of slip in said hydraulic coupling.

15. A power transmission system comprising a driving machine, a driven machine, a hydraulic coupling oi' the kinetic type having a vaned driving part coupled to said driving machine and a vaned driven part coupled to said driven machine, a control member operable for braking one of said machines, two co-operating screw-threaded elements mounted co-axially with said coupling, one of said elements being slidable longitudinally of said coupling and operatively connected with said control member, while the other of said screw-threaded elements is 4 restrained from moving longitudinally of said coupling, and a slipable driving connection between one of said screw-threaded elements and one of said vaned coupling parts, the other of said screw-threaded elements being coupled for rotation with the other of said vaned coupling parts, whereby said screwthreaded elements are constrained to rotate relatively to each other and actuate said control member upon reversal of slip in said hydraulic coupling.

16. A power transmission system comprising a hydraulic coupling of the kinetic type having an impeller member and a runner member, a hydraulic valve operable for varying the torquetransmission capacity of said coupling, differential screw mechanism which connects together said impeller member, said runner member and said valve, said diierential mechanism being associated with a frictional connection which, when slip therein ceases, constrains said differential mechanism to actuate said valve through the agency of part oi.' the power delivered to said coupling.

HAROLD SINCLAIR. 

